The species table published on this website contains links to the distribution maps of 135 eastern U.S. tree species based on Importance Values (IV) derived from Forest Inventory Analysis (FIA) data and a geographical information system (GIS) database of Elbert L. Jr. Little's published ranges.

Between 1971 and 1977, Elbert L. Jr. Little, Chief Dendrologist with the U.S.D.A. Forest Service, published a series of maps of tree species ranges based on botanical lists, forest surveys, field notes ad herbarium specimens. These published maps have become the standard reference for most U.S. and Canadian tree species ranges.

The U.S.D.A. Forest Service's FIA units are charged with periodically assessing the extent, timber potential and health of the trees in the United States. We have created a spatial database of individual species IV based on the number of stems and basal area of understory and overstory trees using FIA data from more than 100,000 plots in the eastern United States. The IV ranges from 0 to 100 and gives a measure of the abundance of the species. (See our climate change tree atlas for details). We have aggregated the plot-level IV to 20km cells.

Both sets of maps (Little's ranges and IV based on FIA data) are available for download from the species table.

Species Table Specifics:

135 eastern United States species are presented three ways:

By species number (FIA code - alphabetical listing within softwoods [1-299], and hardwoods [300-980]

By common name

By Latin name
By clicking on the column header, you can sort the table by that classification.

You can view the distribution maps (jpeg images that contain both Little's ranges and FIA-based IV) at three different scales depending on the column button you select:

Entire US-Canada extent (Species No. column)

Little's range extent (Common Name column)

Eastern US (east of 100th meridian) extent (Latin Name column).

You can also download the ESRI's ArcView shapefile for Little's range by clicking on little.shp and the asciigrid file (ArcInfo Grid/ArcView Spatial Analyst) for IV by clicking on asciigrid.

Note, however that while Little's range maps are vector based and span both U.S. and Canada, the FIA-based IV maps are raster based and span only east the 100th meridian in the U.S.. GIS Metadata and help on how to use the species table are provided as links next to the species table.

The Little's range maps were digitized by either the RWU NE-4153's GIS lab or the U.S. Geological Survey (USGS). In some cases we have edited the USGS digitized maps to correct errors. For all the maps, we added a new field called CODE that distinguishes among water-bodies (0), species present (1) and "species absent" islands (2). You can find out if a species has been originally digitized by the USGS by bringing the mouse over the species number (1st column in the species table). A popup box will appear if it is USGS digitized map; no popup box appears if we have digitized the map.

We also provide several choices of boundary maps to provide context to the range or FIA-based IV maps. To get the boundary shapefiles and projection information, please go to the Boundary Maps section.

The U.S. Geological Survey is digitizing Little's published maps. We have use some of them in this database and would like to acknowledge their effort.

Many of Little's range maps were digitized in our lab. We acknowledge Becki Wells for her tireless work on the almost obsolete and not too friendly digitizer! Thanks also to Brian McComb who contributed to the digitizing efforts.

We would again like to acknowledge the U.S. Forest Service's Forest Inventory & Analysis division whose data we used for deriving the Importance Value of tree species.

The data have been quality-checked, but we cannot be sure there are no errors remaining. Therefore, no guarantees can be given on the accuracy of the maps and data provided. We would appreciate learning of any errors you may uncover.